Steering system for vehicles

ABSTRACT

A steering system for vehicles includes an oscillating axle, a pair of wheel lean members individually transversely rockably coupled to the opposite ends of the axle, a pair of king pins associated with each of the wheel lean members, a pair of spindle housings individually pivotally movable on each wheel lean member through the king pins and having an integral steering arm thereon, a pair of wheels individually rotatable with respect to the spindle housings, a tie rod directly connecting each of the steering arms, and at least one steering cylinder connected between one of the steering arms and the axle to provide a high angle of steer for increased vehicle maneuverability and a minimum of interaction between wheel lean and steering functions.

United States Patent [19] Campbell et al.

[ STEERING SYSTEM FOR VEHICLES [75] Inventors: John J. Campbell; CullenP. Hart,

both of Decatur, Ill.

[73] Assignee: Caterpiller Tractor Co., Peoria, Ill.

[22] Filed: Aug. 18, 1972 [21] Appl. No.: 281,919

[52] US. Cl. l80/79.2 R, 280/111 [51] Int. Cl B62d 5/06, B62d 7/00 [58]Field of Search 180/79, 79.1, 79.2 R, l80/79.3, 79.4, 79.5, DIG. 1, DIG.2; 280/111 [56] References Cited UNITED STATES PATENTS 3,398,808 8/1968Heckenhauer 280/111 X 2,216,930 10/1940 Altemus 180/79.3 X 2,323,6827/1943 Schoenrock 180/79 X 2,625,232 l/l953 Lado 280/111 X 2,796,9456/1957 Dye et al.... 180/79.2 R 3,446,305 5/1969 Cannon 280/111 X3,527,316 9/1970 Jones et al. l80/79.2 R UX [451 Jan. 8, 1974 PrimaryExaminer-Robert S. Ward, Jr. Att0meyRalph E. Walters [5 7] ABSTRACT Asteering system for vehicles includes an oscillating axle, a pair ofwheel lean members individually transversely rockably coupled to theopposite ends of the axle, a pair of king pins associated with each ofthe wheel lean members, a pair of spindle housings individuallypivotally movable on each wheel lean member through the king pins andhaving an integral steering arm thereon, a pair of wheels individuallyrotatable With respect to the spindle housings, a tie rod directlyconnecting each of the steering arms, and at least one steering cylinderconnected between one of the steering arms and the axle to provide ahigh angle of steer for increased vehicle maneuverability and a minimumof interaction between wheel lean and steering functions.

PATENTEBJAN 81974 SHEET 2 [1F 3 PATENTEDJM'I 14.

SHEET 3 [IF 3 STEERING SYSTEM FOR VEHICLES BACKGROUND OF THE INVENTIONSeveral wheel-type vehicles, such as conventional motor graders, have anoscillating front axle with wheel lean members rockably disposed onopposite ends of the axle on a longitudinal pivot pin. These leanmembers are typically provided with a pair of outwardly oriented flangesto provide a king pin mounting of a spindle system on which a wheel isrotatably mounted. Further, the upper extremities of these wheel leanmembers are connected together by a wheel lean link, and a hydraulicallyactuated extendible cylinder is provided to lean this mechanism.

One of the major problems that such axles experience is the excessiveinteraction between the wheel lean and steering functions. For example,if such a motor grader is making a turn to the left, the angle of steershould not be affected to any significant degree even though the wheelsare leaned during the turn to counter the forces being felt by the motorgrader blade or to counter the drift of the grader due to it beingoperated on side slopes. Not only should these actions be substantiallyindependent, but also the system should be effective for a high angle ofsteer so that the motor grader can turn within a small radius forincreased maneuverability. It is also important that neither the wheellean nor the steering functions should be affected by the oscillation ofthe axle as the vehicle traverses uneven terrain.

Another problem arises in that when steering the inboard wheel must turnto a greater angle than the outboard wheel to obtain a truer wheelrolling motion. In order to control the pivoting of the front wheels sothat their axes would intersect each other near the axis of the rearwheels, various changes must be made to the steering geometry. Thesecorrectional changes, referred to as the Ackermann form of steeringlinkage, result in a more desirable control of the vehicle under avariety of operating conditions, but are perfect for only one turningradius. Therefore, the lengths of the steering arms and associatedcomponents must be chosen so that the mean of the errors throughout thesteering range is maintained at a minimum.

Another difficulty is that the joints of prior art axle assemblies arefrequently subjected to non-uniform torque loading by the action of thehydraulically extendible cylinders used for the wheel lean and steeringfunctions, or by the reverse action of shock loads transmitted throughthe wheels and into the linkage. Such unequal loading results inexcessive twisting of the components to the point of resulting in theirpremature failure.

Further, earthmoving equipment which can benefit by such a steeringsystem is becoming larger, is more heavily horsepowered, and issubjected to greater operational abuse. As a result, the front axlesthereof must be extremely rugged, have a high ground clearance, and berelatively simple in constuction in order to be of maximum value to theuser at a minimum overall cost.

SUMMARY AND OBJECTS OF THE INVENTION Therefore, to overcome theabove-noted problems, it is the object of this invention to provide asteering system for a vehicle having increased maneuverability with aminimum of interaction between the wheel lean and steering functions, aswell as an optimum built-in steering angle correction.

Another object of this invention is to provide a relatively simple axleconstruction which lends itself to a rugged fabrication at a relativelylow cost.

Another object of this invention is to provide an axle constructionwhich has a high ground clearance and a minimum exposure of the criticalcomponents to possible damage by large rocks and dirt clumps over whichthe vehicle may be traveling.

Another object is to provide a relationship of the wheel lean andsteering hydraulic cylinders to the primary pivot axes such thattransmitted forces are essen-' tially in line with the yokes and otherelements of the axle assembly to minimize twisting loads.

Other objects of this invention will become apparent from the followingdescription and accompanying drawings.

BRIEF DESCRIPTIONOF THE DRAWINGS FIG. 1 is a front elevational view ofan oscillating axle embodying the vehicle steering system of thisinvention with the tires shown in broken lines for illustrative clarity.

FIG. 2 is a top plan view of the oscillating axle of FIG. 1.

FIG. 3 is a somewhat enlarged isometric view of one end of theoscillating axle with portions broken away for illustrative convenience.

FIG. 4 is a further enlarged vertical sectional view through the end ofthe oscillating axle shown in FIG. 3 taken generally along the lineIV-IV of FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENT With reference to the drawings,an oscillating axle assembly indicated generally by the referencenumeral- 10 is shown disposed on the front of an elongated vehicle frame11 having a longitudinal axis substantially aligned with the directionof vehicle movement. As best shown in FIG. 2, a pair of forwardlydisposed, transversely arranged, vertical plates 12 and a pair ofrearwardly disposed, transversely arranged, vertical plates 13 on thevehicle frame are adapted to respectively receive a pair oflongitudinally aligned pivot pins 14 and 15 on which the axle assemblyoscillates. A pair of axle stop members 16, individually disposed onopposite sides of the frame 11, limit the angle of oscillation of theaxle assembly to approximately 16 from either side of its horizontallydisposed condition.

The axle assembly 10 includes an elongated axle 17 of rectangular crosssection which is transversely and rockably coupled to the vehicle frame11 on the pin 15 by means of a conventional sealed bearing arrangementshown generally at 20. For increased strength, the axle assembly alsoincludes a pair of forwardly and inwardly angled brace bars 21 which areindividually secured at their rearward extremities to a pair of integralyoke members 22 and 23, respectively, disposed on the outer oppositeends of the axle 17. The forward extremities of the brace bars arerockably coupled to the vehicle frame on the pin 14 by means of a sealedbearing arrangement 24.

On a rearward face 30 of the axle 17 are disposed a pair of horizontallyarranged and rearwardly extending ears 31 in spaced symmetrical relationadjacent to the opposite sides of the frame 11. An upper surface 33 ofthe axle further includes a pair of longitudinally spaced upwardlyextending ears 34.

As best shown in FIG. 2, each of the yoke members 22 and 23 has asubstantially vertically extending rear face providing an overloadlimiting-surface for extremely high angles of steer, as will bedescribed more fully below. These yoke members individually pivotallymount a pair of'right and left bifurcated wheel lean members showngenerally at 40 and 41, respectively, for transverse rockable movement.

With particular reference to the right wheel lean member 40 shown inFIGS. 3 and 4, an outwardly disposed clamping arrangement is showngenerally at 42 for removably securing such right wheel lean member on awheel lean pin 43. An upwardly directed integral arm 44 contains anotherclamping arrangement shown generally at 45 for an upper pivotal joint 46in which a longitudinally oriented pin 47 is removably secured to thewheel lean member. With the axle 17 horizontally disposed and with nowheel lean, an angle of approximately 5 is formed between a truevertical longitudinal plane 50 passing through the pin 43 and a plane 51passing through the axes of the pins 43 and 47.

Referring to FIG. 4, the bifurcated right wheel lean member 40 includesan outwardly directed upper flange 52 and an outwardly directed lowerflange 53 combining to provide a pair of substantially verticallyaligned bores 54 and 55 adapted individually to contain a pair ofsleeve-type bearings 56 and 57, respectively. The sleeve bearings arepreferably of the selflubricating type, and are individually outwardlyprotected from dirt by a protecting cover 60. A bifurcated spindlehousing 61 has an inwardly directed upper flange 62 and an inwardlydirected lower flange 63 contiguously associated within the respectiveflanges 52 and 53 of the wheel lean member. The spindle housing furtherhas a pair of aligned bores 64 adapted individually to receive a pair ofking pins 65 and 66 in oppositely outwardly extended relation. The kingpins are removably secured within their respective bores 64 by a lockpin 67, and are disposed for pivotal movement within the bearings 56 and57 of their associated flanges 52 and 53 to allow steerable rotation ofthe spindle housing 61 with respect to the wheel lean member 40. Athrust washer 70 and a face seal 71 are disposed between the associatedflanges for extending the service life of this pivotal connection.

The bifurcated spindle housing 61 also includes a stepped hollow bore 72which is spaced substantially equidistantly between the flanges 62 and63, and has a downwardly directed axis 73. A pair of spaced antifrictionbearings 74 are received within the stepped hollow bore and rotatablysupport a spindle 75 therewithin. This relationship of the spindlewithin the spindle housing permits the bearings to rotate more slowlyfor increased bearing service life when compared to outwardly rotatingassemblies. A seal group shown generally at 76 and a cap member 77 serveto contain lubricating fluid within the bearing area.

A wheel rim assembly 80 is removably secured to the spindle 75 by aplurality of retaining bolts 81, and a tire 82 is mounted thereon in theusual manner. The downwardly directed axis 73 of the spindle provides :12 camber angle for the tire 82, as respectively shown between a verticalplane 83 and a central plane 84 of the tire passing intermediate thebearings 74. This slight camber angle decreases steering effort.

As shown in the righthand portion of FIG. 1, the left side of axleassembly 10 contains a bifurcated spindle housing 85, a spindle 86, anda tire 87 essentially identical to that described with respect to theright side. A horizontally disposed wheel lean link 90 transverselyconnects the arm 44 and the pivotal joint 46 of the right wheel leanmember 40 with a similar upwardly directed arm 91 and a pivotal joint 92on the left wheel lean member 41. A wheel lean actuating cylinder 93 isconnected at a pivot joint 94 to the axle 17 as by the ears 34, and anactuating rod 95 extends from the cylinder to pivotally connect with thepin 47 at the joint 46. Extension of the actuating rod 95 permitssimultaneous leaning of both wheel lean members 40 and 41 in acounterclockwise direction on the respective pivot pins 43 through thewheel lean link 90.

With continuing reference to FIG. 1, the axle assembly 10 includes awheel lean trapezoidal relationship which assures clearance between theinside surfaces of the tires 82 and 87 adjacent joints 46 and 92 andwherein the distance between the pivot pins 43 at the axle extremitiesis slightly greater than the parallel distance between joints 46 and 92at the ends of the wheel lean link 90. With the axle 17 horizontallydisposed, this results in an angle of approximately 5 between thevertical plane 50 passing through the axis of pivot pin 43, as describedabove in connection with FIG. 4, and the plane 51 passing through theaxis of the pivot pin 43 and the pivotal joint 46. A similar 5 angle ofinclination is experienced on the left side.

In connection with the steering system shown more clearly in FIGS. 2 and3, the right spindle housing 61 preferably includes an integralrearwardly and inwardly angled steering arm 96 having an inwardlydisposed stop surface 97 thereon, though the arm may alternately beremovably secured thereto. The right steering arm 96 is connected to asimilar steering arm 98 integral with the left spindle housing 85through a tie rod 100 having an adjustable length and a pair ofselfaligning balljoints on the ends thereof as shown generally at 101and 102. A pair of horizontally disposed steering cylinders 103 and 104are respectively mounted on the axle 17 through the cars 31 and a pairof self-aligning pivot bearings or ball joints shown generally at 105and 106. A pair of extendible piston rods 107 and 108 are respectivelyconnected to the steering arms 96 and 98 intermediate the ends thereofthrough another pair of self-aligning pivot bearings or ball jointsshown generally at 1 l1 and 1 12. This connection of the piston rods tothe steering arms independent of the tie rod connections at 101 and 102allows geometric flexibility in the design of the linkage proportionsand disposition thereof which is one of the features of the subjectinvention.

it should also be appreciated that only one of the steering cylinders103 or 104 and its corresponding piston rod can be used to replacethe'double steering cylinder arrangement illustrated without departingfrom the spirit of the subject invention.

As shown in FIG. 2, the oscillating axle assembly of the presentinvention provides a steering system which includes a steering geometrytrapezoidal relationship wherein the distance between the left and rightking pins 65 or 66 is greater than the parallel distance between the endconnection 101 and 102 of the tie rod 100. With the tires 82 and 87positioned for substantially straight-line travel, there is provided abuilt-in steering correction angle of approximately 13 between alongitudinally disposed vertical plane 1 13 through the king pins and avertical plane 1 14 through the king pins and the tie rod connection102. This relationship provides a common steering center for both wheelsnear the axis of the rear wheels during one predetermined intermediateturning radius and permits the inboard wheel to turn more sharply thanthe outboard wheel to extend tire life by providing a more nearly truewheel rolling motion.

OPERATION While the operation of the present invention is believedclearly apparent from the foregoing description, further amplificationwill subsequently be made in the following brief summary of suchoperation. As shown in FIG. 1, the axle 17 may be noted as having a higharch profile allowing the vehicle to traverse over very rough terrainwith a relatively high ground clearance. For example, the lowest portionof the axle assembly centrally between the wheel lean members 40 and 41is elevationally close to the elevation of the longitudinal pins 14 andof the axle assembly. The axle 17, the

angle brace bars 21, andthe wheel lean link 90 are not only of ruggedrectangular construction, but are disposed to maximize protection forthe steering cylinders 103 and 104, as well as the wheel lean cylinder93.

With extension of the wheel lean cylinder rod 95, the wheel lean members40 and 41 move in a counterclockwise direction with respect to theirrespective pivot pins 43 so that the wheels are positionable to theirapproximate maximum inclination as shown by the broken line positions 82and 87. Full retraction of the cylinder rod 95 thereafter positions thewheel lean members and the tires toward the maximum clockwise directionas shown by the broken line positions at 82" and 87". Because of thetrapezoidal wheel lean geometry mentioned heretofore, the central plane84 of the tires may be leaned through a range of approximately 20outwardly to approximately 16 inwardly at the top from the true verticalplane 83 of the tire as shown at the righthand portion of FIG. 1.

When the wheel lean members 40 and 41 are transversely rocked on thewheel lean pivot pins 43 as noted above, the steering geometry isinfluenced to only an extremely limited degree. To accomplish this, theelevational disposition of the steering cylinder pivotal connections orball joints 105, 106, 111, and 112 are arranged in a horizontal planepassing approximately through the wheel lean pivot pins as may bevisualized with respect to the elevation view of FIG. 1. The relativelyhigher elevation of the self-aligning pivotal connections 101 and 102 atthe ends of the tie rod 100 are independently chosen so that the tie rodis able to clear the hydraulic steering cylinders 103 and 104 at theextreme lean conditions and is less vulnerable to damage duringmaneuvering of the vehicle over rough obstacles. It is the tie rod thatdetermines the relative angularity between the left and right wheels.

FIGS. 1 and 4 also show that the wheel lean pivot pins 43 are disposedat an elevational position to insure clearance between the top of thewheel lean arms 44 and 91 and the inside annular surface of the wheelrim assemblies 80, and to further be compatible with the effectivelength of the wheel lean cylinder between the pivotal connections 46 and94 within the available space provided.

Because the wheel lean cylinder rod 95 is substantially transversely inline with the king pins 65 and 66 as shown in FIG. 2, detrimentalloading forces and overturning or steering forces from wheel lean areminimized. Further, the wheel spindle housing 61 and the wheel spindleare centered transversely with respect to the main axle beam 17 so thatthe vehicle weight produces substantially no torsional loading of theaxle.

Since the inboard wheel on a turn must turn through a greater angle thanthe outboard angle, the axle assembly 10 of the subject inventionincludes the aforementioned built-in steering correction angle set forthas approximately l3 with respect to FIG. 2. This angle also must bechosen to take into account such factors as the wheel base of the entirevehicle and the distance between the centerlines of the king pins. Ifthe inboard wheel is assumed as establishing the turning radius, theangular movement of the axis of the outboard wheel necessary to coincidewith the intersection of the axes of the inboard wheel and rear wheelsis referred to herein as the Ackermann Error Angle. There is only aslight Ackermann Error Angle for all degrees of steering utilizing thegeometry of the present invention. If a maximum turn to the left is madeunder a condition of no wheel lean, the wheels 82 and 87 are rotateddiffer ent amounts about the king pins 65 and 66 to their respectivebroken line positions 82" and 87" and with the wheels assuming thefollowing typical angles from the longitudinal vertical plane 113.

EXAMPLE:

Left Wheel Right Wheel Ackermann Turn Angle Tum Angle Error Angle 48937.l 3.1

This negative Ackermann Erorr Angle at such maximum turn angle indicatesthat the outboard wheel did not turn far enough. However, this errorrepresents a substantially maximum value, since at some intermediatesteering angle corresponding to one predetermined vehicle turning radiusthe error is zero, with the axes of the wheels passing through the samepoint on the pivot axis of the rear wheels.

With the axle assembly of the present invention, the angular dispositionof each steering cylinder 103 or 104 is independent of the connectionbetween the steering arms 96 and 98 and the tie rod by virtue of havingtwo separate pivotal connection points, such as for example at theconnections 101 and 111. Therefore, the angle of the cylinders relativeto the axle 17, and more particularly the arcuate movement of the balljoints 111 or 1 12 as the steering cylinder rods 107 and 108 arereciprocated between the maximum extended and maximum retractedpositions can be established so that the motion of the ball joints 111or 112 is substantially horizontal and in a plane passing through thewheel lean pins 43 as shown in the righthand portion of FIG. 1 tominimize the effect of lean on steering. As shown in FIG. 4, thelongitudinal vertical plane 50 through the lean pin 43 is positionedrelatively close to the longitudinal vertical plane 113 passing throughthe-king pins 65 and 66 as.represented by distance A therebetween. Thisdistance is chosen for minimum steering error with respect to wheellean. Geometric errors resulting from leaning the wheels about the pins43 during maximum turns tothe right or left are substantially balancedby properly choosing the distance A and relating the 0 steer or straightline travel position of the ball joints 1 11 or 1 12 thereto. Thevertically spaced nature of the king pins 65 and 66 makes it possiblefor the wheel lean pivot pins 43 to be positioned further outwardly thanwith a single king pin and to provide a relatively small distance A. Theangular relationships of thewheels 82 and 87 to the longitudinalvertical plane 113 set forth above with respect to a maximum steeringturn are substantially maintained at these same values throughout theentire range of wheel lean movement, which indicates that there is aminimum of interaction between the wheel lean and steering functionsutilizing the axle assembly of the present invention.

The distance betweenthe longitudinal vertical plane 113 passing throughthe king pins 65 and 66 and the longitudinal vertical plane 83 passingthrough the center of each wheel as represented by the letter B in FIG.4 is also chosen on the basis of several considerations. For example,while it is desirable for distance B to be small in order to reduce theseverity of shock loads from being transmitted from a rough groundsurface condition and the tire 82 back to the reacting steering cylinderrod 107 through the spindle 75 and the spindle housing 61, this distancemust be large enough for clearance between the inside of the tireadjacent the rim ssembly 80 and the various elements of axle assembly asthe wheels are leaned or steered. The ratio of distance B to distance Ais preferably in the range from two to three.

With the wheels at a condition of maximum steer, as illustrated by thebroken line positions of the tires at 82" in FIG. 2, suitable internalstops (not shown) are provided within the steering cylinders 103 or 104to limit the maximum extension of the piston rod 107 or 108. However,under certain conditions of considerable wheel lean and externallyapplied shock loads to the tires, it has been found desirable to limitthe travel of the steering arms 96 and 98 toward the axle 17 by analternate method. Such limiting is achieved by allowing the stopsurfaces 97 to contact the rear faces 35 of their respective yokemembers 22 or 23.

In view of the foregoing, it is readily apparent that the structure ofthe present invention provides an improved oscillating axle assemblywhich affords only a minimum of interaction between the wheel lean andsteering functions, with optimum built-in steering angle correction. Itis of relatively rugged simple construction having maximum resistance todetrimental twisting forces while affording excellent ground clearance.

While the invention has been described and shown with particularreference to the preferred embodiment,

it is apparent that variations might be possible that would fall withinthe scope of the present invention, which is not intended to be limitedexcept as defined in the following claims.

What is claimed is:

1. A steering system for vehicles comprising,

an elongated frame having a longitudinal axis substantially aligned witha predetermined forward and rearward direction of earth traversingmovement of such a vehicle,

axle means rockably coupled to said frame transversely of said axishaving opposite outer ends,

a pair of wheel lean members individually rockably coupled to saidopposite ends of said axle means for swinging movement in asubstantially upright plane,

wheel lean actuation means pivotally mounted on said axle means andeffective to rock said wheel lean members relative to said axle means,

wheel mounting means pivotally mounted on said wheel lean members forswinging movement through a plane substantially normal to said plane ofpivotal movement of said wheel lean members and having a steering armthereon,

tie rod means directly connecting each of said steering arms, and

power means pivotally interconnecting at least one of said steering armsand said axle means and being disposed in substantially horizontallycoplanar relation to said axle means in order to provide a minimuminteraction between the wheel lean and steering functions.

2. The steering system of claim 1 wherein said tie rod means is a singletie rod pivotally connected to each of said steering arms independentlyof the pivotal connection of said power means to at least one of saidsteering arms.

3. The steering system of claim 1 wherein said power means comprises atleast one cylinder and associated extendible piston rod substantiallyhorizontally rearwardly coupled to said axle means and one of saidsteering arms for maximum protection against objects encountered duringsaid earth traversing movement of the vehicle.

4. The steering system of claim 1 including a pair of horizontallylongitudinally disposed wheel lean pins for individually rockablymounting said wheel lean members on said outer ends of said axle means,and a pair of vertically spaced king pins individually positioned aboveand below each of said wheel lean pins and in relatively transverselyclosely spaced relation thereto whereby errors in steering due torocking of said wheel lean members is minimized.

5. The steering system of claim 4 wherein said power means comprises atleast one extendible hydraulic cylinder connected to said steering armat an elevation substantially coinciding with said wheel lean pinwhereby the rocking of said wheel lean members on said axle results inonly a minimum influence on the steering angle.

6. The steering system of claim 1 wherein said wheel mounting meansincludes a spindle housing having a cylindrical bore and bearing meansdisposed in said bore, a spindle rotatably received in said bearingmeans, and a wheel removably secured to said spindle.

7. The steering system of claim 1 wherein said axle means includes anelongated axle having bifurcated opposite ends individually adapted toembrace said wheel lean member, and means individually pivotallymounting said wheel lean members on said ends of the axle.

8. The steering system for vehicles of claim 7 wherein said wheel leanactuation means is pivotally disposed between at least one of said pairof wheel lean members and said axle in elevationally spacedsubstantially coplanar relation with said bifurcated opposite ends ofsaid axle.

9. The steering system of claim 8 including a wheel lean link, and anupwardly extending arm on each of said wheel lean members pivotallyattached to said link whereby said link is substantially horizontallydisposed at an elevational position forwardly adjacent to said wheellean actuation means in shielding relation during said forward earthtraversing movement of the vehicle.

10. A steering system comprising,

an elongated frame having a longitudinal axis,

an axle transversely rockably coupled to said frame and having a pair ofoutwardly disposed opposite 12. The steering system for vehicles ofclaim 11 wherein said wheel lean pin is positioned in a substantiallyhorizontal plane substantially intermediate said upper pin and saidlower pin.

ends, 13. A wheel mounting arrangement for a vehicle a longitudinallyoriented wheel lean pin associated comprising;

with each of said opposite ends, pivotal connection means on thevehicle;

a bifurcated wheel'lean member transversely and bifurcated wheel leanmeans rockably mounted on rockably coupled to each of said opposite endsof said pivotal connection means and having an outsaid axle by saidwheel lean pin, wardly directed upper flange and an outwardly dia wheellean cylinder pivotally mounted on said axle rected lower flangesubstantially equidistantly and effective to rock said wheel leanmembers relaspaced from said pivotal connection means; tive to saidaxle, bifurcated spindle means having an integral steering king pinmeans associated with said wheel lean memarm, an inwardly directed upperflange, and an inber, 5 wardly directed lower flange with the flangesbeing a bifurcated spindle housing having a steering arm substantiallyequidistantly spaced from said pivotal thereon and cooperativelyassociated with said connection means between said upper and lower kingpin means for pivotal turning of said spindle flanges of said wheel leanmeans; housing on each of said wheel lean members and so apair ofvertically spaced king pins individually pivthat said wheel lean pin istransversely closely otally coupling said upper flanges and said lowerspaced with respect to said king pin means for minflanges of saidspindle means and said wheel lean imum steering error with respect towheel lean, means, respectively;

wheel means adapted for rotation with respect to wheel means adapted forrotation on said spindle each of said spindle housings, and means; and

a steering cylinder connected between at least one of powered extendibleretractable steering means pivotsaid steering arms and said axle. allyattached to said steering arm at an elevation 1 l. The steering systemof claim 10 wherein said king corresponding with said pivotal connectionmeans pin means is an upper pin and a lower pin pivotally joinso thatthe influence of wheel lean is minimal on ing said bifurcated spindlehousing and said bifurcate the angle of steer of said wheel means. wheellean member. v 3Q

1. A steering system for vehicles comprising, an elongated frame havinga longitudinal axis substantially aligned with a predetermined forwardand rearward direction of earth traversing movement of such a vehicle,axle means rockably coupled to said frame transversely of said axishaving opposite outer ends, a pair of wheel lean members individuallyrockably coupled to said opposite ends of said axle means for swingingmovement in a substantially upright plane, wheel lean actuation meanspivotally mounted on said axle means and effective to rock said wheellean members relative to said axle means, wheel mounting means pivotallymounted on said wheel lean members for swinging movement through a planesubstantially normal to said plane of pivotal movement of said wheellean members and having a steering arm thereon, tie rod means directlyconnecting each of said steering arms, and power means pivotallyinterconnecting at least one of said steering arms and said axle meansand being disposed in substantially horizontally coplanar relation tosaid axle means in order to provide a minimum interaction between thewheel lean and steering functions.
 2. The steering system of claim 1wherein said tie rod means is a single tie rod pivotally connected toeach of said steering arms independently of the pivotal connection ofsaid power means to at least one of said steering arms.
 3. The steeringsystem of claim 1 wherein said power means comprises at least onecylinder and associated extendible piston rod substantially horizontallyrearwardly coupled to said axle means and one of said steering arms formaximum protection against objects encountered during said earthtraversing movement of the vehicle.
 4. The steering system of claim 1including a pair of horizontally longitudinally disposed wheel lean pinsfor individually rockably mounting said wheel lean members on said outerends of said axle means, and a pair of vertically spaced king pinsindividually positioned above and below each of said wheel lean pins andin relatively transversely closely spaced relation thereto wherebyerrors in steering due to rocking of said wheel lean members isminimized.
 5. The steering system of claim 4 wherein said power meanscomprises at least one extendible hydraulic cylinder connected to saidsteering arm at an elevation substantially coinciding with said wheellean pin whereby the rocking of said wheel lean members on said axleresults in only a minimum influence on the steering angle.
 6. Thesteering system of claim 1 wherein said wheel mounting means includes aspindle housing having a cylindrical bore and bearing means disposed insaid bore, a spindle rotatably received in said bearing means, and awheel removably secured to said spindle.
 7. The steering system of claim1 wherein said axle means includes an elongated axle having bifurcatedopposite ends individually adapted to embrace said wheel lean member,and means individually pivotally mounting said whEel lean members onsaid ends of the axle.
 8. The steering system for vehicles of claim 7wherein said wheel lean actuation means is pivotally disposed between atleast one of said pair of wheel lean members and said axle inelevationally spaced substantially coplanar relation with saidbifurcated opposite ends of said axle.
 9. The steering system of claim 8including a wheel lean link, and an upwardly extending arm on each ofsaid wheel lean members pivotally attached to said link whereby saidlink is substantially horizontally disposed at an elevational positionforwardly adjacent to said wheel lean actuation means in shieldingrelation during said forward earth traversing movement of the vehicle.10. A steering system comprising, an elongated frame having alongitudinal axis, an axle transversely rockably coupled to said frameand having a pair of outwardly disposed opposite ends, a longitudinallyoriented wheel lean pin associated with each of said opposite ends, abifurcated wheel lean member transversely and rockably coupled to eachof said opposite ends of said axle by said wheel lean pin, a wheel leancylinder pivotally mounted on said axle and effective to rock said wheellean members relative to said axle, king pin means associated with saidwheel lean member, a bifurcated spindle housing having a steering armthereon and cooperatively associated with said king pin means forpivotal turning of said spindle housing on each of said wheel leanmembers and so that said wheel lean pin is transversely closely spacedwith respect to said king pin means for minimum steering error withrespect to wheel lean, wheel means adapted for rotation with respect toeach of said spindle housings, and a steering cylinder connected betweenat least one of said steering arms and said axle.
 11. The steeringsystem of claim 10 wherein said king pin means is an upper pin and alower pin pivotally joining said bifurcated spindle housing and saidbifurcated wheel lean member.
 12. The steering system for vehicles ofclaim 11 wherein said wheel lean pin is positioned in a substantiallyhorizontal plane substantially intermediate said upper pin and saidlower pin.
 13. A wheel mounting arrangement for a vehicle comprising;pivotal connection means on the vehicle; bifurcated wheel lean meansrockably mounted on said pivotal connection means and having anoutwardly directed upper flange and an outwardly directed lower flangesubstantially equidistantly spaced from said pivotal connection means;bifurcated spindle means having an integral steering arm, an inwardlydirected upper flange, and an inwardly directed lower flange with theflanges being substantially equidistantly spaced from said pivotalconnection means between said upper and lower flanges of said wheel leanmeans; a pair of vertically spaced king pins individually pivotallycoupling said upper flanges and said lower flanges of said spindle meansand said wheel lean means, respectively; wheel means adapted forrotation on said spindle means; and powered extendible retractablesteering means pivotally attached to said steering arm at an elevationcorresponding with said pivotal connection means so that the influenceof wheel lean is minimal on the angle of steer of said wheel means.